The study authors conducted four different studies in which the mice were randomized into different diet groups and fed one of four diets.

“We were very careful in our research to expose the animals to the equivalent standard sugar dosages of what humans consume,” study author Lorenzo Cohen of the University of Texas M.D. Anderson Cancer Center, told Science World Report. He noted that the lowest dose the mice were fed was 9 teaspoons of sugar a day while the highest dose was 37 teaspoons a day.

According to the American Heart Association (AHA), adult women should only get up to 5 teaspoons (20 grams) of added sugar per day, while adult men should only get up to 9 teaspoons of added sugar per day (36 grams). Children should only get up to 3 added teaspoons of sugar per day (12 grams).

Drink one can of soda (Coke, let’s say), and you’ve already passed your limit; there are as many as 10 teaspoons of sugar in some sodas (or 40 grams).

At six months of age, 30 percent of mice on a starch-control diet had measurable tumors, whereas 50 to 58 percent of the mice on sucrose-enriched diets had developed mammary tumors. The study also showed that numbers of lung metastases were significantly higher in mice on a sucrose- or a fructose-enriched diet, versus mice on a starch-control diet.

Previous research links a Western-style diet to an increased risk of cancer–going along with recent findings published in the journal Nature, suggesting that a higher majority of cancer deaths worldwide are the result of avoidable lifestyle choices.

In this case, the unhealthy choice is poor diet–specifically relating to too much sugar. But it’s not so simple; in other words, not all sugars are created equal. Glucose, a vital nutrient that the body uses to create energy, is not to blame here. Sucrose, or sugar, is made up of both glucose and fructose molecules–and the culprit here is fructose.

Researchers found that the fructose molecule affects 12-LOX (12-lipoxygenase)–a metabolic process that can cause the spread of cancer.

Though researchers are still not certain why fructose causes tumors to grow faster, the researchers noted that it makes 12-LOX more active.

While the study didn’t look at sugar coming from fruit (which has sugar that is still composed of both glucose and fructose)–it’s important to note that fruit contains fiber and nutrients, while sugar from a soda doesn’t.

In addition, too much refined sugar has been linked to an increased risk of obesity, as well as a long list of health issues, including type 2 diabetes, cardiovascular health issues and even dementia.

Health officials continously recommend that we limit refined sugar intake. In fact, last year, the World Health Organization (WHO) recommended that our daily intake of added sugars be reduced from 10 percent of our total energy intake to below 5 percent (6 teaspoons).